Predominance of new G9P[8] rotaviruses closely related to Turkish strains in Nizhny Novgorod (Russia)

Detection and full-genotype determination of rare and reassortant rotavirus A strains in Nizhny Novgorod in the European part of Russia

Reassortant DS-1-like rotavirus A strains have been shown to circulate widely in many countries around the world. In Russia, the prevalence of such strains remains unclear due to the preferred use of the traditional binary classification system. In this work, we obtained partial sequence data from all 11 genome segments and determined the full-genotype constellations of rare and reassortant rotaviruses circulating in Nizhny Novgorod in 2016-2019. DS-1-like G3P[8] and G8P[8] strains were found, reflecting the global trend. Most likely, these strains were introduced into the territory of Russia from other countries but subsequently underwent further evolutionary changes locally. G3P[8], G9P[8], and G12P[8] Wa-like strains of subgenotypic lineages that are unusual for the territory of Russia were also identified. Reassortant G2P[8], G4P[4], and G9P[4] strains with one Wa-like gene (VP4 or VP7) on a DS-1-like backbone were found, and these apparently had a local origin. Feline-like G3P[9] and G6P[9] strains were found to be phylogenetically close to BA222 isolated from a cat in Italy but carried some traces of reassortment with human strains from Russia and other countries. Thus, full-genotype determination of rotavirus A strains in Nizhny Novgorod has clarified some questions related to their origin and evolution.

Increase in rotavirus prevalence with the emergence of genotype G9P[8] in replacement of genotype G12P[6] in Sabah, Malaysia

Rotaviruses are major causative agents of acute diarrhea in children under 5 years of age in Malaysia. However, a rotavirus vaccine has not been included in the national vaccination program. To date, only two studies have been carried out in the state of Sabah, Malaysia, although children in this state are at risk of diarrheal diseases. Previous studies showed that 16%-17% of cases of diarrhea were caused by rotaviruses and that equine-like G3 rotavirus strains are predominant. Because the prevalence of rotaviruses and their genotype distribution vary over time, this study was conducted at four government healthcare facilities from September 2019 through February 2020. Our study revealed that the proportion of rotavirus diarrhea increased significantly to 37.2% (51/137) after the emergence of the G9P[8] genotype in replacement of the G12P[8] genotype. Although equine-like G3P[8] strains remain the predominant rotaviruses circulating among children, the Sabahan G9P[8] strain belonged to lineage VI and was phylogenetically related to strains from other countries. A comparison of the Sabahan G9 strains with the G9 vaccine strains used in the RotaSiil and Rotavac vaccines revealed several mismatches in neutralizing epitopes, indicating that these vaccines might not be effective in Sabahan children. However, a vaccine trial may be necessary to understand the precise effects of vaccination.

[Variability of genes encoding nonstructural proteins of rotavirus А (Reoviridae: Rotavirus: Rotavirus A) genotype G9P[8] during the period of dominance in the territory of Nizhny Novgorod (central part of Russia) (2011-2020)]

INTRODUCTION

In Russia, rotavirus A is the main cause of severe viral gastroenteritis in young children. The molecular features that allow a rotavirus of a particular genotype to gain an evolutionary advantage remain unclear, therefore, the study of the genetic diversity of rotaviruses based on genes encoding nonstructural proteins (NSPs) responsible for the reproduction of the virus in the cell is an urgent task.

OBJECTIVE

To study the genetic diversity of rotaviruses of genotype G9P[8], which dominated Nizhny Novgorod in 20112020, based on genes encoding nonstructural proteins.

MATERIALS AND METHODS

Rotavirus-positive samples were subjected to PCR-genotyping and sequencing of NSP1 NSP5 genes. Phylogenetic analysis was carried out in the MEGA X program.

RESULTS

In the period 20112020, G9P[8] rotaviruses with four variants of the NSP2 gene were co-circulating in Nizhny Novgorod. New alleles were noted in 2012 (N1-a-III), 2016 (N1-a-IV) and in 2019 (N1-a-II). The appearance of new variants of other genes occurred in 2014 (E1-3, NSP4), 2018 (T1-a3-III, NSP3) and in 2019 (A1-b-II, NSP1). NSP2 gene had the most variable amino acid sequence (16 substitutions), 2 to 7 substitutions were observed in NSP1, NSP3 and NSP4, NSP5 was conservative.

DISCUSSION

The results obtained are consistent with the literature data and indicate the participation of NSP genes in maintaining the heterogeneity of the rotavirus population.

CONCLUSION

Until 2018, the genetic diversity of rotaviruses in Nizhny Novgorod was determined by the circulation of strains carrying several alleles of the NSP2 gene and conservative genes NSP1, NSP3NSP5. By the end of the study period, new variants of the genotype G9P[8] were formed in the population, carrying previously unknown combinations of alleles of nonstructural genes.

Prevalence and Genetic Diversity of Group A Rotavirus Genotypes in Moscow (2019-2020)

Group A rotavirus (RVA) infection is the leading cause of hospitalization of children under 5 years old, presenting with symptoms of acute gastroenteritis. The aim of our study was to explore the genetic diversity of RVA among patients admitted to Moscow Infectious Disease Clinical Hospital No. 1 with symptoms of acute gastroenteritis. A total of 653 samples were collected from May 2019 through March 2020. Out of them, 135 (20.67%) fecal samples were found to be positive for rotavirus antigen by ELISA. RT-PCR detected rotavirus RNA in 80 samples. Seven G-genotypes (G1, G2, G3, G4, G8, G9, and G12) and three P-genotypes (P[8], P[4], and P[6]) formed 9 different combinations. The most common combination was G9P[8]. However, for the first time in Moscow, the combination G3P[8] took second place. Moreover, all detected viruses of this combination belonged to Equine-like G3P[8] viruses that had never been detected in Russia before. The genotype G8P[8] and G9P[4] rotaviruses were also detected in Moscow for the first time. Among the studied rotaviruses, there were equal proportions of Wa and DS-1-like strains; previous studies showed that Wa-like strains accounted for the largest proportion of rotaviruses in Russia.

[Molecular monitoring of the rotavirus (Reoviridae: Sedoreovirinae: Rotavirus: Rotavirus A) strains circulating in Nizhny Novgorod (2012-2020): detection of the strains with the new genetic features]

INTRODUCTION

The pentavalent rotavirus vaccine has been registered in Russia, however, the vaccination coverage remains low, and an annual increase in the incidence of rotavirus infection is unavoidable. In this regard, molecular monitoring of rotaviruses in order to search for new variants possessing epidemic potential is an urgent task.

MATERIAL AND METHODS

PCR genotyping and VP4 and VP7 genes sequencing were used to characterize rotaviruses circulating in Nizhny Novgorod in 2012-2020. The phylogenetic analysis of the strains was carried out using the BEAST software package.

RESULTS

The spectrum included 17 genotypes with predominance of G9P[8] (37,4%). Detected in this study genotypes G1P[4], G1P[9], G2P[8], G4P[4], G4P[6], G8P[8], and G9P[4] were not previously identified in Nizhny Novgorod. The circulation of DS-1-like strains possessing genotypes G1P[8], G3P[8], G8P[8], or G9P[8] and a short RNA pattern had been shown. Rotaviruses of the common genotypes were genetically heterogeneous and belonged to different phylogenetic lineages and/or sublineages (P[4]-IV-a; P[4]-IV-b; P[8]-3.1; P[8]-3.3; P[8]-3.4 and P[8]-3.6; G1-I; G1-II; G2-IVa-1; G2-IVa-3; G3-1; G3-3; G4-I-c; G9-III; G9-VI).

DISCUSSION

These results extend the available data on the genotypic structure of rotavirus populations in Russia and show the genetic diversity of viral strains. G3P[8] DS-1-like viruses were representatives of the G3-1 lineage, new for the territory of Russia, and had the largest number of amino acid substitutions in the VP7 antigenic epitopes.

CONCLUSION

The emergence and spread of strains with new genetic features may allow rotavirus to overcome the immunological pressure formed by natural and vaccine-induced immunity, and maintain or increase the incidence of rotavirus infection.

Increasing detection of rotavirus G2P[4] strains in Nizhny Novgorod, Russia, between 2016 and 2019

Rotavirus infection is one of the leading causes of acute gastroenteritis in children in their first years of life. We studied the genotypic diversity of rotavirus A (RVA) strains in Nizhny Novgorod, Russia, during the period 2016-19. In total, 4714 samples of faeces from children admitted to the Nizhny Novgorod Hospital for Infectious Diseases with acute gastroenteritis were examined. The share of rotavirus-positive samples was 31.5% in 2016-17. It decreased to 21.6% in 2018-19. In Nizhny Novgorod, all six global types of RVA were detected (G1P[8], G2P[4], G3P[8], G4P[8], G9P[8] and G12P[8]), as well as sporadic samples with genotypes G9P[4], G3P[9], G9P[9], G8P[8], G2P[8], G4P[4], G3P[9]. The fraction of strains with genotype G2P[4] gradually increased from 5.9% in 2016-17 to 39.1% in 2018-19. Simultaneously, the proportion of G9P[8] strains decreased from 63.2% to 27.7% in the same period. Phylogenetic analysis showed that rotaviruses with the G2P[4] genotype carried ubiquitous alleles of the VP7 and VP4 genes during the period of their prevalence: G2-IVa-1 and G2-IVa-3; P[4]-IVa and P[4]-IVb. As rotavirus vaccination is not widely used in the region because it is not included in the national vaccination calendar in Russia so far, the increase in the number of G2P[4] RVA is likely due to natural strain fluctuations.

Genotype constellations of the rotavirus A strains circulating in Nizhny Novgorod, Russia, 2017-2018

Currently, the full-genome-based classification is widely used to investigate rotavirus A (RVA) strains found in different countries around the world. However, the information on the full genotypes of rotaviruses circulating in Russia is limited. Using partial sequencing, this study determined the full genotype constellations of 15 RVA strains in total commonly detected in Nizhny Novgorod (European part of Russia) in 2017-2018, three from each of the following genotypes G1P[8], G4P[8], and G9P[8] and six from G2P[4]. There were two intergenogroup mono-reassortants possessing an identical genotype constellation of G4-P[8]-I1-R1-C1-M1-A1-N1-T1-E2-H1 with the DS-1-like NSP4 gene of probably local origin. A variety of subgenotype lineages and their combinations of Wa-like rotaviruses and genetic heterogeneity among G9P[8] and G1P[8] strains were shown on the basis of phylogenetic analysis of each gene. Moreover, two distinct co-circulating variants that differed in all 11 genome segments were found among DS-1-like rotaviruses.

Phylodynamics of G4P[8] and G2P[4] strains of rotavirus A isolated in Russia in 2017 based on full-genome analyses

Rotavirus A is a dynamically evolving pathogen causing acute gastroenteritis in children during the first years of life. In the present study, we conducted a phylodynamic analysis based on the complete sequences of 11 segments of rotaviruses with the G4P[8] and G2P[4] genotypes isolated in Russia in 2017. Since rotavirus has a segmented genome, our analysis was performed using the Bayesian approach based on separate samples of nucleotide sequences for each gene of the strains studied. For the strain with the genotype G4P[8], the most likely geographical locations of the nearest common ancestor were Russia (VP7, VP4, VP6), China (VP1), Thailand (VP3), Belgium (NSP1), Hungary (VP2, NSP2, NSP3), Italy (NSP4) and Japan (NSP5). For the strain with the G2P[4] genotype, India (VP7, VP4, VP6, NSP1, NSP4), Malawi (VP2, NSP2, NSP3), Australia (VP1), Italy (NSP5) and Bangladesh (VP3). The closest common ancestor of the strain with the genotype G4P[8] circulated in 2001-2012, depending on the gene being analyzed. For the strain with the G2P[4] genotype, the closest common ancestor dates from 2006 to 2013.

Genetic diversity of group A rotaviruses in Moscow in 2018-2019

Here, we present the results of a study in which 639 samples obtained between October 2018 and April 2019 from patients with symptoms of acute gastroenteritis were tested for the presence of a rotavirus infection. The antigen of group A rotavirus was detected in 160 samples (25% of those tested). To study the genetic diversity of group A rotavirus, RNA was isolated from the samples, and polymerase chain reaction combined with reverse transcription (RT-PCR) with primers specific for the VP4, VP6, and VP7 genes of group A rotaviruses was performed. At least one fragment of the group A rotavirus genome was found in 101 samples (15.8%). These fragments were sequenced, and their G and P genotypes-as well as their combinations-were determined. The predominant G genotypes were G9 (35.8% of all genotyped samples) and G4 (28.4%), but the rare G12 genotype was also found (3.0%). The dominant P genotype was P[8]. The spectrum of certain G/P combinations of genotypes included seven variants. The most common variants were G9P[8] (37.2%) and G4P[8] (30.2%).

Molecular-Genetic Characterization of Human Rotavirus A Strains Circulating in Moscow, Russia (2009-2014)

Enteric viruses are the most common cause of acute gastroenteritis (AGE) in young children and a significant public health problem globally. Hospital admissions of children under 5 years of age with diarrhea are primarily associated with group A rotavirus (RVA) infection. In this retrospective study, the population structure of viruses linked to AGE etiology in young children hospitalized with AGE in Moscow was evaluated, and molecular characterization of RVA strains was performed. Fecal specimens were collected from children under 5 years old hospitalized with AGE between 2009 and 2014 in Moscow, Russia. Multiplex real-time reverse transcription PCR was used to detect enteric viruses and for G/[P]-genotyping of isolated RVAs. Sequencing of RVA VP7 and VP4 cDNA fragments was used to validate the data obtained by PCR-genotyping. The main causes for hospitalization of children with AGE were RVA (40.1%), followed by noroviruses (11.4%), while adenoviruses, astroviruses, sapoviruses, enteroviruses, and orthoreoviruses were detected in 4.7%, 1.9%, 1.4%, 1.2%, and 0.2% of samples tested, respectively. Nosocomial infections, predominantly associated with RVAs and noroviruses, were detected in 24.8% of cases and occurred significantly more frequently in younger infants. The predominant RVA genotype was G4P[8], detected in 38.7% of RVA-positive cases, whereas genotypes G1P[8], G9P[8], G3P[8], and G2P[4] were found in 11.8%, 6.6%, 4.2%, and 3.3% of cases, respectively. Together, the presence of circulating RVA strains with rare VP7 and VP4 gene variants (G6 and P[9]) highlights the need to conduct continuous epidemiological monitoring of RVA infection.

Phylogenetic analysis of human G9P[8] rotavirus strains circulating in Jiangsu, China between 2010 and 2016

Rotavirus A (RVA) is the leading cause of acute viral gastroenteritis in children under 5 years of age worldwide. G9P[8] is a common RVA genotype that has been persistently prevalent in Jiangsu, China. To determine the genetic diversity of G9P[8] RVAs, 7 representative G9P[8] strains collected from Suzhou Children's Hospital between 2010 and 2016 (named JS2010-JS2016) were analyzed through whole-genome sequencing. All evaluated strains showed the Wa-like constellation G9-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1. Furthermore, phylogenetic analysis revealed that the VP7 genes of all strains clustered into lineage G9-III and G9-VI. With the exception of strain JS2012 (P[8]-4), the VP4 sequences of all strains belonged to the P[8]-3 lineage. Sequencing further revealed that amino acid substitutions were present in the antigenic regions of the VP7 and VP4 genes of all strains. Moreover, there were multiple substitutions in antigenic sites I and II of the nonstructural protein 4 (NSP4) genes, whereas the other NSP genes were relatively conserved. In conclusion, our phylogenetic analysis of these 7 G9P[8] strains suggests that RVA varied across regions and time. Therefore, our findings suggest that continued surveillance is necessary to explore the molecular evolutionary characteristics of RVA for better prevention and treatment of acute viral gastroenteritis.